JPH07113134A - Production of sintered titanium alloy - Google Patents

Abstract

PURPOSE:To produce a sintered titanium alloy, which is free from component segregation and remaining of coarse pores and has high density and in which coarsening of crystalline particles is inhibited and higher mechanical properties are provided, under general compacting and sintering conditions at the time of producing a sintered titanium alloy by a material powder mixing method using an ultralow chlorine titanium powder prepared by a hydrogenation- dehydrogenation process. CONSTITUTION:A powder for alloying elements addition is regulated so that a powder of 3-8mum average particle diameter comprises 20-40wt.% and the balance consists of a powder of 8-15mum average particle diameter. In addition, a titanium powder of 45-150mum particle diameter comprises 40-70% of the whole weight of the powderes used and the balance consists of a titanium powder of 10-45mum particle diameter, by which the high density sintered titanium alloy can be obtained. Further, as the powder of 8-15mum average particle diameter for alloying elements addition, a powder containing at least one kind among Y, Er, and B by the amount equivalent to 0.03-0.5wt.% of this alloy is used. By this method, the growth of crystalline particles can be inhibited and high mechanical properties can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a sintered titanium alloy by powder metallurgy. More specifically, the present invention relates to a method for producing a sintered titanium alloy by the elementary powder mixing method.

[0002]

2. Description of the Related Art Powder metallurgy is one of the near-net shape technologies for directly manufacturing a product having a shape close to the final shape from a material, and is a method for manufacturing a titanium alloy product having poor workability, formability or machinability. Are suitable. Particularly, in the elementary powder mixing method, titanium powder and alloying element-adding powder are mixed and filled in a container, which is molded at a pressure of 3 to 8 ton / cm ² to obtain a green compact, and then 1100-1300 in vacuum. This is a method in which sintering and alloying heat treatment are performed simultaneously at 1 ° C for 1 to 8 hours, and since soft titanium powder occupies the majority before sintering, it has good formability and has a precise shape at room temperature. There is an advantage that you can get a body. Here, as the titanium powder, Hunter Sponge Fine (HSF), which is a by-product of titanium sponge produced by the sodium reduction method, or ultra-low chlorine titanium produced by the so-called hydrodehydrogenation method, which is hydrogenated and pulverized after being dissolved and then dehydrogenated Powder (HDH powder) is used.

However, the elementary powder mixing method has a drawback that the fatigue strength is low because the sintering density is insufficient and the internal pores remain even after the above-described sintering at high temperature for a long time. As a method of solving this, there is a method of further performing hot isostatic pressing (HIP) after sintering to completely eliminate the internal pores and improve the fatigue strength, but the manufacturing cost is significantly increased.

On the other hand, Japanese Patent Publication No. 2-50172 discloses a titanium powder having an average particle size of 40 to 177 μm and an average particle size of 0.5 to 20 μm to which high energy is imparted by pulverization.
A method for obtaining a density of 99.0% or more with respect to a theoretical value at the sintering stage by using alloy forming particles of m (powder for adding alloy element) and increasing the surface energy of the powder is described. . However, when soft titanium powder containing 0.1 wt% or less of oxygen such as Hunter Sponge Fine (HSF) is used, this method produces 99.0% or more under general molding and sintering conditions. Ultra-low chlorine titanium powder (HDH powder) manufactured by the hydrodehydrogenation method, which can be densified, but is hard and inferior in moldability because it inevitably contains more than 0.1% by weight of oxygen in the manufacturing process. However, it was difficult to increase the density under general molding and sintering conditions. Also, HDH powder contains less than 20 ppm of chlorine and has no effect of suppressing crystal grain coarsening due to chlorine, so that it is different from the case of using HSF containing 0.05 to 0.2% by weight of chlorine during sintering. There is also a defect that the structure becomes coarse and mechanical properties, particularly fatigue properties are deteriorated.

In addition to this, Japanese Patent Publication No. 2-50172
In the method described in Japanese Patent Laid-Open Publication No. 2003-242242, when a very fine powder for adding an alloy element having an average particle size of 0.5 to 3 μm is used, although the density after sintering is high, the powder agglomerates to cause component segregation, resulting in mechanical failure. However, there is a problem in that the physical properties, particularly the fatigue strength, are reduced. In addition, when the alloying element-added powder having an average particle size of 15 μm or more is used, although the density after sintering is high, coarse pores locally remain, and mechanical properties, particularly fatigue strength are lowered. There was a point.

Meanwhile, 1980 American Institute of Minin
g., Metallurgical, and PetroleumEngineers, Inc. "Titanium '80 Science and Technology", page 1185, Ti or Ti-6Al-4V.
When Er or Y is added to the ingot at about 1% by weight or less,
It is known that these oxides are generated in the alloy and suppress the grain growth, so that the structure is refined. Applying this knowledge to the elementary powder mixing method, Y, Er, Y ₂ O ₃ , Er ₂
When O ₃ or a B-containing compound such as TiB ₂ , B ₄ C or BN is added alone, the contact of the titanium powder or the alloying element-adding powder is hindered and the movement of the powder surface is pinned. There is a drawback that the binding properties are further deteriorated, and as a result, the fatigue strength is further reduced.

[0007]

SUMMARY OF THE INVENTION Therefore, the present invention is an elementary powder mixing method using an ultra-low chlorine titanium powder containing oxygen of more than 0.1 wt% produced by the hydrodehydrogenation method.
In the method for producing a sintered titanium alloy, a sintered titanium alloy having high density and high mechanical properties without segregation of components and coarse pores locally remaining under the same general molding and sintering conditions as in the past It aims at providing the method of manufacturing. Further, it is an object of the present invention to provide a method for producing a sintered titanium alloy having higher mechanical properties by suppressing coarsening of crystal grains.

[0008]

In order to achieve the above object, the present invention provides (1) 0.1 produced by a hydrodehydrogenation method.
20% by weight or more and less than 40% by weight of the alloying element-containing powder used in the method for producing a sintered titanium alloy by an elemental powder mixing method using an ultra-low chlorine titanium powder containing oxygen in an amount of more than 50% by weight. The particle size is 3 μm or more and less than 8 μm, and the remaining alloy element-adding powder has an average particle size of 8 μm or more and 1
A method for producing a sintered titanium alloy, characterized in that it is less than 5 μm, and (2) 40% or more and 70% or less of the total weight of the powder used is titanium powder having a particle size of 45 μm or more and 150 μm or less, and the remaining Titanium powder has a particle size of 10 μm or more 4
A method for producing a sintered titanium alloy according to (1), characterized in that the particle size is less than 5 μm, and (3) 0% of the sintered titanium alloy is used as a powder for adding an alloy element having an average particle size of 8 μm or more and less than 15 μm. (1) and (2), characterized in that a powder containing at least one of Y, Er and B in an amount corresponding to 0.03% by weight or more and 0.5% by weight or less is used.
It is a method for producing a sintered titanium alloy as described.

Here, the alloy element addition powder is a mother alloy powder containing two or more elements of Ti or alloy elements, or a single metal powder of alloying elements. Further, Y, Er, B contained in the powder for adding the alloying element may be a simple substance, or a compound such as an oxide such as Y ₂ O ₃ , Er.
₂ O ₃ , B ₄ C or the like may be used. In the present invention,
In addition to Ti and alloying elements and oxygen of 0.4 wt% or less, titanium alloys inevitably contain less than 0.4 wt% of Fe (for non-Fe-containing alloys), N, C, H and other impurities. May be included.

[0010]

The present invention will be described in detail below. The present inventors have used HDH powder which contains oxygen in an amount of more than 0.1% by weight and is inferior in formability to HSF but can be stably supplied, and segregates components locally or locally remains at a high density in the sintering stage. In order to obtain a sintered titanium alloy having no coarse pores and high mechanical properties, research was repeated on the particle size distribution of the powder for adding the alloying element and the HDH powder, the oxygen content, and the structure control of the sintered material. As a result, it has been found that by optimizing the particle size distribution of the powder used, the density of the sintered material is significantly increased, the segregation of the components is eliminated, and coarse mechanical pores are not left, so that high mechanical properties can be achieved. Further, they have found that by devising a method of adding a substance that suppresses crystal grain growth, coarsening of the structure can be suppressed and higher mechanical properties can be achieved.

In the present invention 1 (the invention of claim 1), in an elementary powder mixing method using HDH powder containing oxygen in an amount of more than 0.1% by weight, 20% by weight or more and 40% by weight or more of the alloying element addition powder used. %, The average particle size is 3 μm or more and less than 8 μm, and the remaining alloy element addition powder has an average particle size of 8 μm or more and less than 15 μm. In this way, by adding the alloying element addition powder controlled to a specific particle size at a specific ratio, the voids between the powders are filled up and the filling effect is increased,
The defects of HDH powder, which is inferior in formability, can be sufficiently compensated, and a high-density sintered material can be obtained without component segregation and coarse pores, and as a result, high mechanical properties can be achieved.

Here, the average particle size of the alloying element addition powder is set to 3
When the particle size is less than 3 μm, the powder agglomerates to cause component segregation, and when the particle size is 15 μm or more, a part where the powder is not filled locally occurs and coarse pores remain.
As a result, the mechanical characteristics deteriorate. The powder for adding alloying elements having an average particle size of 3 μm or more and less than 8 μm was set to 20% by weight or more and less than 40% by weight of the powder for adding alloying elements because the ratio of the coarse powder for adding alloying elements was increased when it was less than 20% by weight. However, the effect of improving the filling rate by filling the voids between the powders is not sufficient, and if it is 40% by weight or more, the amount of fine powders increases, and these agglomerate during mixing to cause component segregation, resulting in deterioration of mechanical properties. This is because.

According to the second aspect of the present invention (the invention of claim 2), the particle size of HDH powder, which has a high oxygen content and is inferior in formability to HSF, is determined by the total weight of powder used (when a titanium alloy is produced by a raw powder mixing method). 40% or more and 70% or less of the total weight of powder used) has a particle size of 40 μm or more and less than 150 μm, and the rest has a particle size of 10
It was decided to limit the thickness to at least μm and less than 45 μm. As a result, in addition to the effect of improving the filling rate as described above by limiting the particle size distribution of the alloying element-added powder, the filling effect of filling voids in the titanium powder is also improved, and a higher density sintered material can be obtained. As a result, high mechanical properties can be achieved. Here, the particle size of the HDH powder is 10 μm or more and 150 μm
The reason for setting the particle size to m or less is that if the particle size is less than 10 μm, the fine titanium powder is so active that it is difficult to handle for safety. This is because if the particle size is larger than 150 μm, the filling rate of the powder is lowered and a sufficient sintered density cannot be obtained, resulting in poor mechanical properties. Furthermore, HDH with a particle size of 45 μm or more and 150 μm or less
The amount of the powder used is set to 40% or more and 70% or less of the total weight of the powder used because the ratio of titanium powder having a particle size of less than 45 μm is relatively increased when the amount is less than 40%, and the oxygen content of the product is increased to increase the mechanical strength. This is because the mechanical properties deteriorate rapidly, and if it exceeds 70%, the amount of coarse powder increases, the sintering density decreases, and the mechanical properties deteriorate.

The present invention 3 (the invention of claim 3) is a powder for adding an alloy element having an average particle size of 8 μm or more and less than 15 μm,
It was decided to use a powder containing at least one of Y, Er, and B corresponding to 0.03% by weight or more and 0.5% by weight or less of the alloy. This is intended to further improve mechanical properties, particularly fatigue properties, by making the structure finer in addition to improving the sintering density.

However, as described in the section of the prior art, when Y, Er, B or their compounds are directly added, the sintered density is remarkably reduced. Therefore, in the present invention, in order to suppress the crystal grain coarsening and reduce the structure fineness without lowering the sintered density, a substance that suppresses the crystal grain growth is used in advance in the alloy element addition powder. I decided. That is, when Y, Er, B or a compound containing these compounds is used as a powder for adding an alloy element in a state in which the alloy element covers the Y, Er, B or a compound containing these, titanium powders containing titanium, titanium, etc. It is possible to improve the sintering density without hindering the contact between the alloy element and the alloy element and without disturbing the movement of the powder surface during sintering. However, on the other hand, Y, Er, B or these compounds inhibit the movement of crystal grain boundaries and suppress the coarsening of the structure.

Here, the average particle diameter of the alloying element-containing powder containing at least one of Y, Er, and B in advance is 8 μm.
It should be above 15 μm. This is because if the average particle size is less than 8 μm, Y, Er, B or these compounds are lost during the pulverizing step during powder production or during powder mixing, and the sintering characteristics deteriorate as in the case of direct addition. This is because when the thickness is 15 μm or more, the above-mentioned lack is not caused, but a portion where the powder is not filled locally is formed, and coarse pores remain and the mechanical properties are deteriorated. Also Y,
The amount of addition of Er and B is set to 0.03% by weight or more and 0.5% by weight or less of the titanium alloy because the addition amount is less than 0.03% by weight and the effect of microstructure refinement is not recognized. If 0.5% by weight or less, a sufficient effect has already been obtained, and if more than 0.5% by weight is added, Y, Er, B
Alternatively, it is because a large lump of these compounds is formed, which becomes a starting point of fracture and deteriorates mechanical properties.

[0017]

The present invention will be described in more detail with reference to the following examples. The sample used for the test was prepared by the following steps.
That is, powders in a predetermined ratio are mixed and filled in a molding container, and cold isostatic pressing (CI) is performed at a pressure of 4.9 ton / cm ^2.
After P) was performed to produce a green compact, sintering was performed at 1250 ° C. for 2 hours in a vacuum of 1 × 10 ⁻³ Pa to produce a cylindrical test piece having a diameter of about 15 mm and a length of about 150 mm. Sintered density (relative density) measurement, β particle size measurement, elongation measurement by a tensile test, and fatigue strength measurement by a rotating bending fatigue test were performed on this sintered titanium alloy. The oxygen content of some samples was measured. Here, the relative density is the density when the density of the sample obtained when the alloys of the same composition are manufactured by the melting method is 100%, and the fatigue strength is 10 ⁷ even if the number of repetitions reaches 10 ^7. The load stress that does not break was evaluated.

First, conventional examples (test numbers 1 to 6) will be described. Two types of titanium powder, HSF and HDH powder, in which a powder having a particle size of 10 μm or more and less than 45 μm and a powder having a particle size of 45 μm or more and 150 μm or less are mixed at a weight ratio of 15:85, are used, as shown in Table 1. Titanium powder and alloying element addition powder are mixed and Ti-
6Al-4V sintered titanium alloy was produced. HSF here
Contains 0.1% by weight or less of oxygen, the HDH powder contains 0.3% by weight of powder having a particle size of 10 μm or more and less than 45 μm, and 0.15% by weight of powder of particle size of 45 μm or more and 150 μm or less. ing.

The case where HSF is used (test numbers 1, 2, 3 in Table 1) and the case where HDH powder is used (test numbers 4, 5, 6 in Table 1) are compared. Test No. 1 in which HSF was used as the titanium powder and the alloy element-added powder having an average particle size of 10 μm had a high sintered density, and both elongation and fatigue strength were similar to those of the HIP-treated material. Test No. 4, in which HDH powder was used for titanium powder and alloy element addition powder having an average particle size of 10 μm was used, the sintered density was 9
It is as low as 8.5% and has low elongation and fatigue strength. This is HDH
This is because the powder has a higher oxygen content than HSF and is inferior in moldability. Further, in Test Nos. 2 and 5 in which powders for adding alloying elements having an average particle diameter of 2 μm were used and HSF and HDH powders were used as titanium powders respectively, the filling rate was improved to 99.5.
Has reached a high sintered density of over%. However, in both cases, segregation of the components occurs, so the elongation and fatigue strength are low. Further, the average β-particle size of Test No. 5 is as large as four times or more that of Test No. 2. This has a chlorine content of 0.1% by weight for HSF and 20 pp for HDH powder, which has the effect of suppressing crystal grain coarsening.
This is because there is a large difference with m or less, and the test refining test using HDH powder did not have the effect of refining the structure.

HSF is used for titanium powder and the average particle size is 1
Test number 3 using the powder for adding alloy elements of 7 μm is
Although the sintered density was improved, the coarse powder of the alloying element addition locally left large voids, and both elongation and fatigue strength were low. HD to titanium powder
Test No. 6, which uses H powder and uses an alloy element addition powder having an average particle size of 17 μm, is inferior in moldability to HDH powder as compared with HSF, and has a coarse alloy element addition element. Does not improve and has low elongation and fatigue strength.

Next, the present invention 1 will be described. As titanium powder, HDH powder having a particle size of 10 μm or more and less than 45 μm and containing 0.3% by weight of oxygen, and a particle size of 45 μm or more and 15
HDH powder containing 0. 5 um or less and 0.15 wt% oxygen was mixed and used at a weight ratio of 15:85. Powders for adding alloy elements as shown in Table 2 were mixed with this titanium powder, and Ti-6Al-4V and Ti-5Al- were mixed.
A 2.5Fe sintered titanium alloy was prepared.

Ti-6Al-4V (Test No. 7 of Table 2)
In No. 15), the test number 7 using the alloying element-added powder having the average particle diameter of 2 μm reached the sintering density of 99.5%, but the segregation of the components caused the elongation and the fatigue strength to increase. Low. Test No. 10 using the alloying element-added powder having an average particle size of 17 μm has a sintered density of 98.9.
%, But coarse voids remain locally, and the elongation and fatigue strength are low. In the powder for alloying element addition, the use amount of the powder having an average particle size of less than 8 μm is 15%, which is less than the amount specified in the present invention 1, the test number 11 is relatively large in the amount of powder having an average particle size of 8 μm or more. It is not possible to sufficiently fill the voids and the sintered density is as low as 98.7%, and the elongation and fatigue strength are also low values. The average particle size is 8μ
In Test No. 15, in which the amount of powder less than m is 45%, which is larger than the amount specified in Invention 1, a large amount of fine powder causes agglomeration and segregation of components, and elongation and fatigue strength are low.

On the other hand, in Test Nos. 8, 9, 12, 13, and 14, which are the examples of the present invention 1, the effect of filling the voids between the powders by using the alloying element-adding powder having the optimum particle size distribution without segregation of the components. As a result, in all cases, the sintered density reached 99% or higher, and the elongation reached 14% or higher and the fatigue strength reached 300 MPa or higher.

Similar results were obtained with Ti-5Al-2.5Fe (test numbers 16 to 20 in Table 2). That is, Test Nos. 16 and 20 in which the ratio of the powder for alloying element addition is outside the range specified in the present invention 1 are caused by insufficient segregation density due to a decrease in filling rate and segregation of components due to powder aggregation. The values of elongation and fatigue strength are low. on the other hand,
Test Nos. 17, 18, and 19, which are examples of the present invention 1,
All of them are 99.2 due to the effect of filling the voids between the powders without segregation of the components by using the powders for adding alloy elements with the optimum particle size distribution.
% Of sintered density is reached, and elongation of 17% or more and 3
It shows a fatigue strength of 40 MPa or more.

Next, the present invention 2 will be described. That is, HDH powder and powders for adding various alloy elements were added in the proportions shown in Table 3 to Ti-6Al-4V and Ti-5Al-2.
It mixed so that it might become 5Fe, and the test piece was produced on the conditions mentioned above. The amount of oxygen in the HDH powder used here has a particle size of 10
0.30% by weight in the case of powder having a particle size of at least μm and less than 45 μm, 45
0.15% by weight for powders having a size of μm to 150 μm, 1
0.12 for powders greater than 50 μm and less than 180 μm
The amount of chlorine is 20 ppm or less.
Table 4 shows the respective sintered densities, oxygen contents, average β particle diameters, elongations, and fatigue strengths.

HDH having a particle size of 45 μm or more and 150 μm or less
Test Nos. 21 and 29 in which the ratio of the powder is 75% or more of the upper limit value of the amount specified in the present invention 2 is 45 μm or more 1
Since the proportion of coarse HDH powder having a particle size of 50 μm or less is large, the filling rate is low, and therefore the sintering density is low and the elongation and fatigue strength are low. The ratio of HDH powder having a particle size of 45 μm or more and 150 μm or less is 35%, which is less than or equal to the lower limit value of the amount defined in the present invention 2. Test Nos. 28 and 31 have a ratio of fine HDH powder having a particle size of 10 μm or more and less than 45 μm. Sintered density is 9 because there are many
Although it is as high as 9.7%, the oxygen content that causes deterioration of mechanical properties is as high as 0.35% by weight or more, and elongation and fatigue strength are low.

The average particle size is larger than 150 μm and 180 μm
Test No. 24, in which 5% of HDH powder of m or less was added, the voids between the coarse powders were not sufficiently filled and the sintered density was low,
Elongation and fatigue strength are also low. Test Nos. 25 and 26 in which the average particle diameter of the powder for alloying element addition is less than or equal to the range specified in the present invention 1 within the range specified by the present invention 2 in the particle size and the ratio of the titanium powder are respectively powders. The elongation and fatigue strength are low due to the segregation of components due to aggregation and the retention of large pores due to coarse powder.

On the other hand, test Nos. 22, 23, 27 and 30 corresponding to the examples of the present invention 2 have the effect of optimizing the particle size distribution of the alloy element addition powder of the present invention 1 as well as the particles of titanium powder. Since the diameter and the ratio were set within the ranges specified in the present invention 2 to suppress the increase of the oxygen amount and to further improve the effect of filling the voids between the powders, a high sintered density of 99.5% or more was reached and 17% or more. High elongation and high fatigue strength of 320 MPa or more were obtained.

Next, the present invention 3 will be described. Powders for alloying element addition of the types and amounts shown in Tables 5 and 6 (continuation of Table 5) and 50% of the total weight of the powders used were made to have a particle size of 45 μm
HDH powder containing 0.15% by weight or less of oxygen at 150 μm or less and the balance HDH powder containing 0.30% by weight of oxygen at a particle size of 10 μm or more and less than 45 μm, and mixed. 6Al-4V or Ti-5
A sintered titanium alloy in which Y, Er, B or a compound thereof was dispersed in Al-2.5Fe was produced.

The test numbers 32 to 35 in Table 5 are, respectively,
It corresponds to the conventional method when powders of Y, Y ₂ O ₃ , Er ₂ O ₃ and B ₄ C are directly added. On the other hand, test Nos. 36 to 52 in Tables 5 and 6 show that the alloying element-added substances (60Al-40V, TiAl, TiFe) and Y, Y ₂ are used so that Y, Er, and B have predetermined amounts.
Powder for adding alloy elements (60Al-40V) prepared by mixing O ₃ , Er ₂ O ₃ , and B ₄ C powders, melting them under vacuum arc, and crushing.
-Y, 60Al-40V-Y ₂ O ₃ , 60Al-40V-Er ₂ O ₃ , 60Al-40V-
B is a _{4 C, TiAl-Y 2 O} 3, TiFe-Y 2 O 3) when used.

Test Nos. 32 to 35 in which powders of Y, Y ₂ O ₃ , Er ₂ O ₃ and B ₄ C were directly added were all used for addition of titanium powder or alloying elements of titanium alloy base material composition. Since the contact of powder (60Al-40V) was hindered and the surface movement of powder was pinned to further deteriorate the sintering characteristics of HDH powder, only a low sintered density of 96% or less was obtained, and elongation and fatigue strength were obtained. Both are extremely low.

On the other hand, Y, Y ₂ O ₃ , Er ₂ O ₃ , B ₄ C
Test Nos. 40 to 43, 45 to 48, 50, and 51 using the powder for adding alloy elements having an average particle size of 10 μm added with Y, Er, B, or Test Nos. 23 and 30 to which these compounds are not added ( Compared with Table 4), the sintered density is 9
It is equivalent to 9.5% or more, and the average β particle size is about 1/5 or less. Therefore, the elongation and the fatigue strength are higher, and the fatigue strength is 380 at Ti-6Al-4V.
MPa or more, Ti-5Al-2.5Fe is 440 MPa or more, which is extremely high. This is the effect that Y, Er, B or their compounds do not hinder the contact of titanium powder or alloy elements, do not hinder the movement of the powder surface, hinder the movement of grain boundaries and suppress the coarsening of the structure. is there.

However, Y, Y ₂ O ₃ , Er ₂ O ₃ and B ₄
Test Nos. 36 to 39 and 44 using the alloying element-added powder having an average particle size of 6 μm containing C have an average particle size of 6 μm.
Since it is fine, Y, Er, B in the crushing and mixing process
Alternatively, if these compounds are missing, Y, Y ₂ O ₃ , Er ₂
The state is the same as when O ₃ and B ₄ C are directly added, and the sintered density is 98.
It was as low as 5% and both elongation and fatigue strength were low.

Test No. 49 shows almost no change in sintered density, average β-grain size, elongation and fatigue strength as compared with Test No. 23 in which Y, Er, B or a compound thereof is not added. The effect of adding ₂ O ₃ was hardly recognized. This is because the amount of Y added was as low as 0.02% by weight, which is less than or equal to the lower limit of the amount specified in Invention 3. In Test No. 52, the β particle size was fine, but the elongation and fatigue strength were low. This is because the amount of Y added is as high as 0.55% by weight, which is equal to or more than the upper limit of the amount specified in the present invention 3, so that a coarse lump of Y ₂ O ₃ is generated, which becomes a starting point of fracture and mechanical properties are increased. This is the result of deterioration.

[0035]

[Table 1]

[0036]

[Table 2]

[0037]

[Table 3]

[0038]

[Table 4]

[0039]

[Table 5]

[0040]

[Table 6]

[0041]

As described above, 0.1% by weight produced by the hydrodehydrogenation method by applying the present invention.
In a method for producing a sintered titanium alloy by an elemental powder mixing method using an ultra-low chlorine titanium powder containing more than 90% oxygen, component segregation and local residue remain under the same general molding and sintering conditions as before. It is possible to produce a sintered titanium alloy having high density and high mechanical properties, without the presence of coarse pores. Furthermore, it is possible to suppress the coarsening of crystal grains and manufacture a sintered titanium alloy having higher mechanical properties.

Front Page Continuation (72) Inventor Takao Horiya 20-1 Shintomi, Futtsu City, Chiba Nippon Steel Co., Ltd.

Claims (3)

[Claims] 1. A method for producing a sintered titanium alloy by an elementary powder mixing method using an ultra-low chlorine titanium powder containing oxygen exceeding 0.1% by weight produced by a hydrodehydrogenation method. 20% by weight or more of the powder for adding alloy elements 4
A method for producing a sintered titanium alloy, characterized in that less than 0% by weight has an average particle size of 3 μm or more and less than 8 μm, and the remaining powder for alloying element addition has an average particle size of 8 μm or more and less than 15 μm. 2. 40% to 70% of the total weight of the powder used
The method for producing a sintered titanium alloy according to claim 1, wherein the following is a titanium powder having a particle size of 45 μm or more and 150 μm or less, and the remaining titanium powder has a particle size of 10 μm or more and less than 45 μm. 3. As a powder for adding an alloy element having an average particle size of 8 μm or more and less than 15 μm, 0.03 of the sintered titanium alloy is used.
The amount of Y, Er,
The method for producing a sintered titanium alloy according to claim 1 or 2, wherein a powder containing at least one kind of B is used.